Rock stable penetration device and rock stable penetration testing method

Abstract

The invention discloses a rock stable permeation device which comprises a high-pressure gas source generation unit, a stable-pressure water supply unit and a permeation unit, the pressure-stabilizing water supply unit comprises a pressure-stabilizing tank with a built-in airbag, the top of the airbag is provided with a T-shaped three-way ball valve, the top of the pressure-stabilizing tank is provided with a water inlet and an exhaust port, and the bottom of the pressure-stabilizing tank is provided with a water supply port with an on-off valve; the permeation unit comprises a supporting and fixing base, a permeation cylinder is fixed to the supporting and fixing base in a threaded connection mode, a water outlet is formed in the position, close to the top, of the cylinder wall of the permeation cylinder, and an anti-overflow sealing ring is arranged at the cylinder bottom of the permeation cylinder; the T-shaped three-way ball valve is communicated with an air inlet pipeline with a pressure regulating valve, and the air inlet end of the air inlet pipeline is communicated with an air outlet of the high-pressure air source generating unit; the water supply port is communicated with a water supply pipeline with a pressure gauge, and the water outlet end of the water supply pipeline hermetically penetrates through the supporting and fixing base and is communicated with the cylinder cavity of the permeation cylinder. The device has the advantages that the rock penetration test is easily completed, the influence of stress on the rock sample is effectively overcome, and the accuracy of the test result is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of rock testing, in particular to a rock stability penetration device capable of automatically supplying high-pressure water. The invention also relates to a rock stability penetration testing method. Background Art

[0003] The main purpose of the rock permeability dissolution test is to study the changes in the permeability of rocks under dissolution. Through this test, we can better understand the impact of dissolution on the pore structure and permeability of rocks, and then evaluate the stability and durability of rocks in specific environments. It is widely used in geological exploration, oil and gas field development, groundwater flow research and other fields.

[0004] At present, the research on rock permeability dissolution test focuses on the seepage-chemistry-stress coupling of rock. The research in this field aims to explore the changing law of rock fracture permeability characteristics and rock fracture mechanism under the joint action of multiple factors. However, in the existing rock permeability dissolution test process, the internal pores of the rock will be compressed and reduced due to the confining pressure under the stress, resulting in a decrease in permeability, which affects the accuracy of the test results. The dissolution effect of mineral particles inside the rock under chemical action is very small. Therefore, in order to truly reflect the changes in rock permeability characteristics under the action of seepage dissolution, it is very necessary to develop a rock stable permeability device that can automatically supply high-pressure water under no confining pressure conditions, and a method for using the device to conduct rock permeability tests. Summary of the invention

[0005] The purpose of the present invention is to provide a rock stability infiltration device capable of automatically supplying high-pressure water in view of the defects of the prior art. At the same time, the present invention also relates to a rock stability infiltration test method for the rock stability infiltration device.

[0006] To achieve the above purpose, the present invention can adopt the following technical solutions: The rock stable infiltration device described in the present invention comprises a high-pressure gas source generation unit, a pressure-stabilizing water supply unit and a permeation unit which are arranged in sequence from left to right; the pressure-stabilizing water supply unit comprises a pressure-stabilizing tank with a built-in air bag, a T-type three-way ball valve is arranged on the top of the air bag, a water inlet and an exhaust port are arranged on the top of the pressure-stabilizing tank, and a water supply port with an opening and closing valve is arranged at the bottom; the permeation unit comprises a supporting base, a permeation cylinder is screwed and fixed on the supporting base, the inner side of the permeation cylinder is an up-and-down through-type cylinder cavity for loading the rock sample to be tested, a drainage port is arranged near the top of the cylinder wall of the permeation cylinder, and an overflow-proof sealing ring which is sealed and pressed on the supporting base is arranged at the bottom of the permeation cylinder; wherein, an air inlet pipeline with a pressure regulating valve is connected to the T-type three-way ball valve, and the air inlet end of the air inlet pipeline is connected to the air outlet of the high-pressure gas source generation unit; the water supply port is connected to a water supply pipeline with a pressure gauge, and the water outlet end of the water supply pipeline is sealed and connected to the cylinder cavity of the permeation cylinder through the supporting base.

[0007] Furthermore, the high-pressure air source generating unit is an air compressor.

[0008] Furthermore, the infiltration cylinder is a truncated cone-shaped cylinder that is smaller at the top and larger at the bottom.

[0009] The present invention also relates to a rock stability permeability testing method, comprising the following steps: S1, rock sample preparation Step 1: Drill a truncated cone-shaped rock core according to the cylinder cavity structure of the permeable cylinder, and pour a layer of expansion fast-setting cement mortar on the outer periphery of the rock core. After the expansion fast-setting cement mortar is completely dried, a rock sample specimen matching the cylinder cavity of the permeable cylinder is obtained; Step 2: Place the prepared rock sample under standard curing conditions and cure it to 14 days old, then wipe off the moisture on the surface of the rock sample, roll a layer of melted paraffin on the surface as a sealing material and let it stand until it is naturally air-dried, thus completing the rock sample preparation; S2, device installation Step 1: Preheat the permeation tube to 60-70℃, then press the rock sample into the preheated permeation tube from bottom to top using a screw press, and ensure that the bottom surface of the rock sample is flush with the bottom surface of the permeation tube, and the top surface of the rock sample is flush with the bottom edge of the drainage port near the top of the permeation tube wall, ensuring that the drainage port can drain normally, and release the pressure of the screw press after the permeation tube cools down naturally; Step 2: Fix the permeable cylinder containing the rock sample on the supporting base by fixing bolts, and place an anti-overflow sealing ring between the permeable cylinder and the supporting base to seal the rock sample in the cylinder; Step 3: Seal and insert the water supply pipeline through the bottom wall of the self-supporting base to ensure that the water outlet of the water supply pipeline is in contact with the bottom surface of the rock sample inside the infiltration tube, and at the same time connect the water inlet of the water supply pipeline to the water supply port of the pressure-stabilizing tank; Step 4: connect the air inlet pipeline to one of the passages of the T-type three-way ball valve on the top of the air bag of the pressure-surge tank, and connect the air inlet end of the air inlet pipeline to the air outlet of the high-pressure air source generating unit; S3, penetration test Step 1: Close the on-off valve on the water supply port, adjust the T-type three-way ball valve to allow the air bag to communicate with the atmosphere outside the pressure-suppressing tank, open the water inlet and exhaust port on the top of the pressure-suppressing tank, and inject water into the pressure-suppressing tank to compress the air bag; Step 2: After the water filling in the pressure-stabilizing tank is completed, close the water inlet and the exhaust port, adjust the T-type three-way ball valve to make the air bag and the air inlet pipeline conduct, open the high-pressure gas source generation unit, adjust the pressure regulating valve on the air inlet pipeline to input gas into the air bag, the air bag expands and compresses the water in the pressure-stabilizing tank, and at the same time open the on-off valve on the water supply port, and pump the water into the bottom surface of the rock sample in the infiltration tube at a certain pressure, and the pressure value is displayed in real time on the pressure gauge; Step 3: When the water pressure value displayed on the pressure gauge stabilizes at the specific pressure value required for the permeability test, start timing and continue observing for 24 hours. Use a measuring cup to collect the seepage water flowing out of the drainage port near the top of the permeability tube wall to complete the record of the rock sample seepage volume within 24 hours. Step 4: According to the seepage rate Q, seepage time t, pressure gauge pressure value P, and cross-sectional area A and height L of the rock sample, calculate the rock sample permeability coefficient K=QL / AP and complete the permeability test.

[0010] The advantage of the present invention is that the high-pressure gas source generating unit continuously and stably inflates the pressure-stabilizing water supply unit, so that the air bag in the pressure-stabilizing tank expands, the water in the squeezing tank flows into the infiltration unit, and the water is continuously and stably squeezed onto the bottom wall of the rock sample in the infiltration tube, thereby easily completing the rock infiltration test, and providing a rock stable infiltration test device and method capable of continuous and automatic high-pressure water supply, which can provide continuous and stable infiltration pressure for the rock infiltration test. At the same time, the infiltration tube itself will not squeeze the rock sample, effectively overcoming the influence of stress on the rock sample, avoiding the compression of the internal pores of the rock sample and the reduction of permeability, and ensuring the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of the present invention.

[0012] Figure 2 This is a permeability coefficient diagram of a rock sample permeability test in a certain area of ​​Xinjiang. DETAILED DESCRIPTION

[0013] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0015] like Figure 1 As shown, the rock stable infiltration device described in the present invention includes a high-pressure gas source generation unit, a pressure-stabilizing water supply unit and a infiltration unit which are arranged in sequence from left to right.

[0016] Specifically, the high-pressure gas source generating unit is an air compressor (the DLX-ACT1500 air compressor produced by Delixi Electric Co., Ltd. which can be directly purchased on the market can be used); the air compressor mainly includes a compressor body 1 and a gas cylinder 2 connected thereto, the compressor body 1 is fixed to the outer wall of the gas cylinder 2 through a connecting frame 3, and an air outlet 4 is also provided on the compressor body 1, and a pair of walking push wheels 5 and a pair of fixed legs 6 are provided on the outer wall of the gas cylinder 2 on the opposite side of the compressor body 1, and a handle 7 for easy grip is also provided at one end of the gas cylinder 2.

[0017] The pressure-stabilizing water supply unit includes a pressure-stabilizing tank 8, in which an air bag 9 is provided in the inner cavity of the pressure-stabilizing tank 8. The top of the air bag 9 is connected to a T-type three-way ball valve 10 located outside the pressure-stabilizing tank 8. At the same time, a water inlet 11 and an exhaust port 12 connected to the inner cavity of the pressure-stabilizing tank 8 are also provided on the top of the pressure-stabilizing tank 8. A water supply port 13 connected to the inner cavity of the pressure-stabilizing tank 8 is also provided at the bottom of the pressure-stabilizing tank 8. An opening and closing valve 14 is provided on the water supply port 13. The opening and closing valve 14 can be a manual valve, and of course it can also be an electrically controlled valve that can automatically control the opening and closing.

[0018] The infiltration unit includes a supporting base 15, on which a permeation cylinder 16 is screwed and fixed by bolts. The permeation cylinder 16 is a truncated cone-shaped cylinder with a small top and a large bottom, and its inner side is a vertical through-type cylinder cavity for loading the rock sample to be tested. A drainage port 17 is provided near the top of the cylinder wall of the permeation cylinder 16, and an anti-overflow sealing ring 18 is provided at the bottom of the cylinder that is sealed and pressed on the supporting base 15.

[0019] In addition, an air inlet pipeline 19 is connected to one of the ports of the T-type three-way ball valve 10, and the air inlet pipeline 19 is provided with a pressure regulating valve 20 that can be adjusted at any time. The air inlet end of the air inlet pipeline 19 is connected to the air outlet on the compressor body 1, thereby forming an air path connection between the high-pressure gas source generation unit and the pressure-stabilizing water supply unit; a water supply pipeline 21 is also connected to the water supply port 13 of the pressure-stabilizing tank 8, and the water supply pipeline 21 is provided with a pressure gauge 22 that can be observed in real time. The water outlet end of the water supply pipeline 21 is sealed from bottom to top through the supporting base 15 to form a connection with the inner cylinder cavity of the permeation cylinder 16, thereby forming a water path connection between the pressure-stabilizing water supply unit and the permeation unit. Of course, multiple permeation units can also be arranged, and in this case, the water supply pipeline 21 is connected to each permeation unit through a branch pipeline.

[0020] The present invention also relates to a rock stability permeability testing method, which uses the rock stability permeability device and specifically comprises the following steps: S1, rock sample preparation Step 1: Drill a truncated cone-shaped rock core to be tested according to the barrel structure of the permeable tube 16, and pour a layer of expansion fast-setting cement mortar on the periphery of the rock core. After the expansion fast-setting cement mortar is completely dried, a rock sample 23 that matches the barrel cavity of the permeable tube 16 is obtained as a test piece; specifically, a cylindrical rock core with a diameter of 150 mm can be drilled, and a section with a height of 150 mm can be cut off and placed in the center of a truncated cone-shaped mold with an upper bottom diameter of 175 mm, a lower bottom diameter of 185 mm, and a height of 150 mm. Then, the expansion fast-setting cement mortar is poured in the mold groove around the rock core, and finally a rock sample 23 that matches the permeable tube 16 is obtained. The cone-shaped rock sample 23 has an upper bottom diameter of 175 mm, a lower bottom diameter of 185 mm, and a height of 150 mm, which matches the cylinder cavity dimensions of the penetrating cylinder 16 (the upper diameter of the cylinder cavity is 174.8 mm, the lower diameter of the cylinder cavity is 185 mm, and the height is 153 mm); wherein the expansive fast-setting cement mortar is used as an early strength agent, and its mix ratio is 1:0.65:1 for water, lime, and sand. In addition, 20% of the weight of cement is added to the water, lime, and sand mixture. Gypsum and calcium chloride of the same weight as the gypsum are added. The expansive fast-setting cement mortar can enable the final rock sample 23 to quickly gain strength in a short period of time.

[0021] Step 2: Place the prepared rock sample 23 under standard curing conditions (temperature 20±3°C, relative humidity above 90% is the standard curing condition), and cure it to 14 days old. Then wipe off the moisture on the surface of the rock sample 23, and roll a layer of melted paraffin on its surface as a sealing material. After standing until it is naturally dried, the rock sample preparation is completed.

[0022] S2, device installation Step 1: First, preheat the infiltration tube 16 to 60-70°C, then press the rock sample 23 from bottom to top into the preheated infiltration tube 16 using a screw press, and ensure that the bottom surface of the rock sample 23 is flush with the bottom surface of the infiltration tube 16. At this time, the top surface of the rock sample 23 is just flush with the lower edge of the drain port 17 near the top of the tube wall of the infiltration tube 16, ensuring that the drain port 17 can drain water normally. After the infiltration tube 16 cools down naturally, release the pressure of the screw press.

[0023] Step 2: Fix the permeable cylinder 16 containing the rock sample 23 on the supporting base 15 by fixing bolts, and place an anti-overflow sealing ring 18 between the permeable cylinder 16 and the supporting base 15 to seal the rock sample 23 in the cylinder. The anti-overflow sealing ring 18 can be a rubber gasket or a silicone gasket.

[0024] Step 3: Seal and insert the water supply pipe 21 through the bottom wall of the self-supporting base 15 to ensure that the water outlet of the water supply pipe 21 is in contact with the lower bottom surface of the rock sample 23 inside the infiltration tube 16, and at the same time connect the water inlet of the water supply pipe 21 to the water supply port 13 of the pressure-stabilizing tank 8.

[0025] Step 4: Connect the air intake pipe 19 to one of the passages of the T-type three-way ball valve 10 connected to the air bag 9 at the top of the pressure-stabilizing tank 8, and connect the air intake end of the air intake pipe 19 to the air outlet 4 of the compressor body 1 in the high-pressure air source generating unit to complete the installation layout of the entire device.

[0026] S3, penetration test Step 1, close the on-off valve 14 on the water supply port 13, adjust the T-type three-way ball valve 10 to connect the airbag 9 with the atmosphere outside the pressure-stabilizing tank 8, open the water inlet 11 and the exhaust port 12 on the top of the pressure-stabilizing tank 8, connect a water pipe to the water inlet 11 to inject water into the pressure-stabilizing tank 8 to compress the airbag 9.

[0027] Step 2, after the water filling in the pressure-stabilizing tank 8 is completed, the water inlet 11 and the exhaust port 12 are closed, and the T-type three-way ball valve 10 is adjusted to the air bag 9 and the air inlet pipeline 19 are connected. At this time, the compressor body 1 of the high-pressure gas source generating unit is opened, and the pressure regulating valve 20 on the air inlet pipeline 19 is adjusted to allow the gas to be input into the air bag 9. As the air bag 9 expands, the water in the pressure-stabilizing tank 8 will be compressed. At the same time, the opening and closing valve 14 on the water supply port 13 is opened, and the water is pumped into the lower bottom surface of the rock sample 23 in the infiltration tube 16 at a certain pressure. The pressure value can be displayed in real time on the pressure gauge 22.

[0028] Step 3: When the water pressure value displayed on the pressure gauge 22 stabilizes at the specific pressure value required for the permeability test (the initial water pressure is 0.01 MPa), start timing and continue observing for 24 hours. At the same time, use a measuring cup to collect the seepage water flowing out of the drainage port 17 near the top of the permeability tube 16 wall, and then complete the seepage volume record of the rock sample 23 within 24 hours.

[0029] Step 4: According to the seepage rate Q, the seepage time t, the pressure value P on the pressure gauge 22, and the actual size of the rock sample 23 (cross-sectional area A, height L), the rock sample permeability coefficient K=QL / AP is calculated to complete the entire permeability test.

[0030] Take the rock sample permeability test in a certain area of ​​Xinjiang as an example: The Western Region conglomerate is named as the Western Region conglomerate because it is mainly distributed in the periphery of the Tarim Basin, the Tianshan Mountains and the piedmont basins of the Kunlun Mountains. At present, there are few research papers on the Western Region conglomerate, and they are mainly focused on geological causes. The research on the engineering properties of the Western Region conglomerate is almost blank. The main reason is that the Western Region conglomerate is mostly distributed in the Tarim Basin and the southern foot of the Tianshan Mountains in Xinjiang. The region is remote and the engineering development is relatively late. In addition, affected by many factors, the development of large-scale water conservancy and hydropower engineering projects in Xinjiang has been lagging for a long time. At the same time, for the Western Region conglomerate, a geological body formed by natural changes, engineers often regard it as a special soil. The parameter selection method of combining test results with reduced parameters is very arbitrary, which also restricts the further research progress of the Western Region conglomerate. At present, Xinjiang is vigorously carrying out the construction of water conservancy and hydropower projects. More and more water conservancy and hydropower projects are gradually being built in the Western Region conglomerate area. Therefore, it is necessary and urgent to carry out research on the engineering properties of the Western Region conglomerate, especially the permeability characteristics.

[0031] Due to the long-term seepage water effect on the conglomerate in the Western Region, a large amount of calcium and mud cement will be lost, gradually forming a granular body, and the anti-seepage stability will be greatly reduced, which has a significant adverse effect on the anti-seepage of the dam foundation and the seepage stability of the hydropower project. In addition, the seepage erosion / dissolution is difficult to detect from the appearance. Once a large cavity is formed, the rock's anti-seepage ability will decrease rapidly, and it is very easy to produce seepage deformation, affecting its mechanical properties, causing landslides or even dam collapses, making the project lose its integrity in a short period of time, and affecting the life of the project.

[0032] The test samples were taken from the Xiyu conglomerate rock samples in a certain area of ​​Xinjiang. The core drill used a handheld rock coring machine, and the core diameter was 150mm. The rock samples taken from the horizontal sampling point had larger cementation particles, which were considered to be coarse-grained cementation; the rock samples taken from the vertical sampling point had finer cementation particles, which were considered to be fine-grained cementation.

[0033] (1) Sample cutting The core is cut into 150mm high. The core is cut by DGQ8.00A multifunctional stone cutting machine. Due to the large size of the core, it is difficult to control the flatness of both ends of the core, so the cutting accuracy of the cutting machine and the feed speed of the operator are required to be high.

[0034] (2) Secondary pouring With reference to the permeability and permeability deformation test of coarse-grained soil (SL237-056-1999), the rock core is placed in the center of a truncated cone mold that matches the size of the barrel cavity of the permeable cylinder 16. The inner wall of the truncated cone mold is roughly equal to the gap around the rock core sample. Then, expansive fast-setting cement mortar is poured around the sample (expandable fast-setting cement mortar is used as an early strength agent, and its mix ratio is 1:0.65:1 for water, ash, and sand, and 20% of the weight of cement is added to the water, ash, and sand mixture. Gypsum and calcium chloride are equal to the weight of gypsum) to make a rock sample 23 with an upper surface diameter of 175mm and a lower surface diameter of 185mm. The sample is placed under standard curing conditions (temperature 20±3℃, relative humidity above 90%) and cured to 14 days old. After that, the surface moisture of the rock sample is wiped dry, and a layer of melted paraffin is rolled on its surface as a sealing material. The rock sample is left to dry naturally to complete the rock sample production.

[0035] (3) Sealing die The infiltration tube 16 is preheated to 60-70°C, and then the rock sample 23 is pressed from bottom to top into the preheated infiltration tube 16 by a screw press, and it is ensured that the bottom surface of the rock sample 23 is flush with the bottom surface of the infiltration tube 16, and the top surface of the rock sample 23 is flush with the lower edge of the drain port 17 near the top of the wall of the infiltration tube 16, ensuring that the drain port 17 can drain water normally, and the pressure of the screw press is released after the infiltration tube 16 is naturally cooled.

[0036] (4) Exhaust The infiltration tube 16 containing the rock sample 23 is fixed on the supporting base 15 by fixing bolts, and an anti-overflow sealing ring 18 for sealing the rock sample 23 in the tube is placed between the infiltration tube 16 and the supporting base 15; the water supply pipeline 21 is sealed and penetrated from the bottom wall of the supporting base 15 to ensure that the water outlet end of the water supply pipeline 21 is in contact with the lower bottom surface of the rock sample 23 inside the infiltration tube 16, and at the same time, the water inlet end of the water supply pipeline 21 is connected to the water supply port 13 of the pressure-stabilizing tank 8.

[0037] An air inlet line 19 is connected to one of the passages of the T-type three-way ball valve 10 on the top of the air bag 9 of the pressure-stabilizing tank 8, and the air inlet end of the air inlet line 19 is connected to the air outlet 4 of the high-pressure air source generating unit. Close the on-off valve 14 on the water supply port 13, adjust the T-type three-way ball valve 10 to connect the airbag 9 with the atmosphere outside the pressure-stabilizing tank 8, open the water inlet 11 and the exhaust port 12 on the top of the pressure-stabilizing tank 8, and inject water into the pressure-stabilizing tank 8 to compress the airbag 9; after the water injection into the pressure-stabilizing tank 8 is completed, close the water inlet 11 and the exhaust port 12, and adjust the T-type three-way ball valve 10 to connect the airbag 9 with the air inlet pipeline 19, open the high-pressure gas source generation unit, adjust the pressure regulating valve 20 on the air inlet pipeline 19 to allow gas to enter the airbag 9, and the airbag 9 expands and compresses the water in the pressure-stabilizing tank 8. At the same time, open the on-off valve 14 on the water supply port 13, and drive the water into the lower bottom surface of the rock sample 23 in the infiltration tube 16 at a certain pressure, and the pressure value is displayed in real time on the pressure gauge 22.

[0038] (5) Apply osmotic pressure When the water pressure value displayed on the pressure gauge 22 stabilizes at 0.01 MPa, start timing and continue observing for 24 hours. After confirming that the seal is good and there is no leakage, pressurize according to the experimental requirements. Use a measuring cup to collect the seepage water flowing out of the drainage port 17 near the top of the wall of the permeable tube 16, and complete the record of the seepage volume of the rock sample 23 within 24 hours.

[0039] The seepage process of the Xiyu gravel under different working conditions is basically the same, which can be roughly divided into several processes such as initial seepage, local seepage liquid accumulation, and seepage liquid filling the surface. The seepage liquid first seeps through the edge of the small-grained gravel, gradually gathers into small water droplets, and then locally gathers (local accumulation is mainly due to the difficulty in controlling the flatness during cutting and secondary pouring, and the sample surface is slightly tilted) and finally fills the entire specimen surface. The seepage process of coarse-grained cemented Xiyu gravel is faster, and the morphological changes are easier to capture. After collecting the seepage liquid, it can be observed that there is obvious sand production around the large-grained gravel. This is the result of the seepage liquid seeping out under the action of osmotic pressure, which is consistent with the phenomenon of sand production in the dam foundation under river erosion in actual engineering, indicating that there is not only dissolution effect but also erosion effect in the seepage process. However, since the amount of sand produced is difficult to collect, the seepage erosion effect of the Xiyu gravel is not discussed.

[0040] (6) Calculation of permeability coefficient According to the seepage rate Q, seepage time t, pressure gauge pressure P and the size of the rock sample (cross-sectional area A, height L), the rock sample permeability coefficient (K=QL / AP) is calculated to complete the permeability test.

[0041] Since the test was conducted under constant pressure, there was no need to collect these data. In order to calculate the permeability coefficient of each period, the seepage flow data is required. However, since the seepage flow of the rock sample in the test is always small, the manual measurement method is directly used. The seepage flow in the period is measured at regular intervals to calculate the average permeability coefficient of the period. It is directly considered as the permeability coefficient at the midpoint in the test analysis. The permeability coefficient is as follows: Figure 2 shown.

[0042] Due to the relatively developed pores and the distribution of a small number of microcracks in the large-size gravels, the permeable fluid in the early stage of pressurization flushes out the fine particles along the seepage channel, and the seepage channel is expanded for a short time. At the same time, according to the results of X-ray diffraction, the sandstone of the Xiyu Formation in the study area contains the clay mineral kaolinite. As one of the most common authigenic clay minerals in the sandstone of the Xiyu Formation, it generally exists in the pore throats and has the ability to expand when exposed to water, especially between particles or rock layers. Therefore, the physical properties and permeability of the rock mass structure are closely related to the distribution characteristics and development degree of kaolinite.

[0043] In the initial stage of the experiment, after the Xiyu Group sandstone and conglomerate rocks came into contact with water, clay minerals quickly absorbed water and expanded, blocking the pore throats, causing the permeability coefficient to drop rapidly from the initial high permeability coefficient. As the seepage progressed, the pressure dissolution effect gradually withdrew from the dominant position, and the mineral dissolution effect of the solution gradually became prominent. Under the action of dissolution, the cementing material dissolved and peeled off, gradually blocking the pore throats, and the permeability coefficient gradually decreased over time. After the internal pores were filled with dissolution, the structure continued to adjust, and the rate of decrease of the permeability coefficient gradually slowed down and gradually stabilized. Fine-grained cementation has a smaller porosity and a denser structure. The cementation ability between gravels is strong, and the ability to resist the penetration and dissolution of the penetrating fluid is strong, so it shows the characteristics of a lower permeability coefficient.

[0044] The internal reaction process of the fine-grained cementation permeability test is divided into three stages, as follows: The first stage: the permeability equilibrium stage. After the rock meets water in the initial 100 hours of the test, the clay minerals quickly absorb water and expand, blocking the pore throats, compressing the internal pore space and reducing the permeability coefficient.

[0045] The second stage: the permeability-dissolution transition stage, the test lasts 100-800 hours, the cementing material is dissolved and stripped under the action of dissolution, the internal pores undergo a complex adjustment stage under the action of fluid filling and dissolution, and the permeability coefficient fluctuates greatly.

[0046] The third stage: the material transport and reaction phase equilibrium stage. After 800 hours of the test, as the internal pore structure of the rock gradually stabilized, the mineral dissolution also stabilized, and the permeability coefficient slowly decreased and stabilized.

[0047] The coarse-grained cemented permeability test process is relatively complicated. In the first 200 hours of the test, the permeate flushed out the fine particles along the seepage channel, the seepage channel was expanded, and the permeability coefficient gradually increased. As the test progressed, the internal pores underwent dissolution and filling, and the structure was constantly adjusted, and the permeability coefficient fluctuated greatly. As the seepage progressed, the test lasted 500-1000 hours, and the cementing material dissolved and peeled off under the action of dissolution, gradually blocking the pore throat, and the permeability coefficient gradually decreased over time. After 1000 hours of the test, the internal pores underwent dissolution and filling, and the structure was constantly adjusted. The rate of decrease in the permeability coefficient gradually slowed down and gradually stabilized.

[0048] When the two groups of rock samples experienced a sudden change in osmotic pressure, the water output increased sharply, and the permeability coefficient showed a short-term mutation phenomenon, accompanied by the seepage of sandy suspended matter at the edge of the gravel. Due to the sudden increase in osmotic pressure, the pores inside the rock sample expanded instantaneously, and the rock sample structure was reconstructed under the new seepage conditions. The permeability coefficient increased in a short time, but as the sediments such as mud and sand eroded by seepage continued to accumulate, the permeability pores of the rock sample decreased again, and the permeability coefficient change trend gradually tended to the pre-osmotic pressure loading. Compared with the fine-grained structure, the overall mutation degree of coarse-grained cementation is more significant, which is the result of the well-developed primary pores and weak cementation between particles.

Claims

1. A rock stabilization infiltration device, characterized in that: It includes a high-pressure gas source generation unit, a pressure-stabilizing water supply unit and a permeation unit which are arranged in sequence from left to right; The pressure-stabilizing water supply unit comprises a pressure-stabilizing tank with a built-in air bag, a T-type three-way ball valve is arranged on the top of the air bag, a water inlet and an exhaust port are arranged on the top of the pressure-stabilizing tank, and a water supply port with an opening and closing valve is arranged on the bottom; The permeation unit comprises a support base, a permeation cylinder is screwed and fixed on the support base, the inner side of the permeation cylinder is a through-type cylinder cavity for loading the rock sample to be tested, a drainage port is arranged near the top of the cylinder wall of the permeation cylinder, and an anti-overflow sealing ring which is sealed and pressed on the support base is arranged at the bottom of the permeation cylinder; Among them, the T-type three-way ball valve is connected to an air inlet pipeline with a pressure regulating valve, and the air inlet end of the air inlet pipeline is connected to the air outlet of the high-pressure air source generating unit; the water supply port is connected to a water supply pipeline with a pressure gauge, and the water outlet end of the water supply pipeline is sealed and connected to the cylinder cavity of the infiltration cylinder through the supporting base.

2. The rock stabilization infiltration device according to claim 1, characterized in that: The high-pressure air source generating unit is an air compressor.

3. The rock stabilization infiltration device according to claim 1, characterized in that: The infiltration cylinder is a truncated cone-shaped cylinder that is small at the top and large at the bottom.

4. A rock stability permeability test method, characterized in that: The steps include: S1, rock sample preparation Step 1: Drill a truncated cone-shaped rock core according to the cylinder cavity structure of the permeable cylinder, and pour a layer of expansion fast-setting cement mortar on the outer periphery of the rock core. After the expansion fast-setting cement mortar is completely dried, a rock sample specimen matching the cylinder cavity of the permeable cylinder is obtained; Step 2: Place the prepared rock sample under standard curing conditions and cure it to 14 days old, then wipe off the moisture on the surface of the rock sample, roll a layer of melted paraffin on the surface as a sealing material and let it stand until it is naturally air-dried, thus completing the rock sample preparation; S2, device installation Step 1: Preheat the permeation tube to 60-70℃, then press the rock sample into the preheated permeation tube from bottom to top using a screw press, and ensure that the bottom surface of the rock sample is flush with the bottom surface of the permeation tube, and the top surface of the rock sample is flush with the bottom edge of the drainage port near the top of the permeation tube wall, ensuring that the drainage port can drain normally, and release the pressure of the screw press after the permeation tube cools down naturally; Step 2: Fix the permeable cylinder containing the rock sample on the supporting base by fixing bolts, and place an anti-overflow sealing ring between the permeable cylinder and the supporting base to seal the rock sample in the cylinder; Step 3: Seal and insert the water supply pipeline through the bottom wall of the self-supporting base to ensure that the water outlet of the water supply pipeline is in contact with the bottom surface of the rock sample inside the infiltration tube, and at the same time connect the water inlet of the water supply pipeline to the water supply port of the pressure-stabilizing tank; Step 4: connect the air inlet pipeline to one of the passages of the T-type three-way ball valve on the top of the air bag of the pressure-surge tank, and connect the air inlet end of the air inlet pipeline to the air outlet of the high-pressure air source generating unit; S3, penetration test Step 1: Close the on-off valve on the water supply port, adjust the T-type three-way ball valve to allow the air bag to communicate with the atmosphere outside the pressure-suppressing tank, open the water inlet and exhaust port on the top of the pressure-suppressing tank, and inject water into the pressure-suppressing tank to compress the air bag; Step 2: After the water filling in the pressure-stabilizing tank is completed, close the water inlet and the exhaust port, adjust the T-type three-way ball valve to make the air bag and the air inlet pipeline conduct, open the high-pressure gas source generation unit, adjust the pressure regulating valve on the air inlet pipeline to input gas into the air bag, the air bag expands and compresses the water in the pressure-stabilizing tank, and at the same time open the on-off valve on the water supply port, and pump the water into the bottom surface of the rock sample in the infiltration tube at a certain pressure, and the pressure value is displayed in real time on the pressure gauge; Step 3: When the water pressure value displayed on the pressure gauge stabilizes at the specific pressure value required for the permeability test, start timing and continue observing for 24 hours. Use a measuring cup to collect the seepage water flowing out of the drainage port near the top of the permeability tube wall to complete the record of the rock sample seepage volume within 24 hours. Step 4: Based on the seepage rate Q, seepage time t, pressure gauge pressure value P, and cross-sectional area A and height L of the rock sample, calculate the rock sample permeability coefficient K=QL / AP and complete the permeability test.

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